This invention relates to a chemical sterilization process for articles such as contact lenses. More particularly, the invention concerns an improved apparatus adapted to be employed in said chemical sterilization process.
The sterilization of contact lenses is currently done by a number of different processes. Some processes employ heat, either in a dry sterilization environment, or with a sterilized saline or similar solution. A further process has also been developed which employs an anti-microbial sterilizing solution such as hydrogen peroxide (H.sub.2 O.sub.2).
The present invention concerns an apparatus specifically designed for use with the latter (hydrogen peroxide) type of sterilization technique. One particularly useful method and apparatus is disclosed in prior U.S. Pat. No. 4,013,410, also assigned to the assignee of this application, to which reference is invited for background material concerning this type of sterilizing process.
Briefly, the hydrogen peroxide solution which is employed is of a relatively weak concentration, for example, no more than on the order of 3% solution of hydrogen peroxide in water. In this sterilizing process it is important to insure that the hydrogen peroxide solution, or any remnants thereof, are completely absent from the lenses before the lenses are reinserted by the wearer. Accordingly, the heretofore applied processes operate to neutralize the hydrogen peroxide solution well before the lenses are removed from the apparatus and replaced in the eye of the wearer.
Generally speaking, the process employed by the above referenced patent uses a catalytic agent such as platinum, which will produce a chemical reaction resulting in neutralization or decay of the hydrogen peroxide. Essentially, a free oxygen molecule is liberated and the hydrogen peroxide is reduced to water. Preferably, the process is arranged to take place over a period of several hours of time, depending on the nature of the catalytic agent and the initial strength of the original sterilizing solution. Accordingly, it is generally recommended that the user employ the process overnight in order to assure full decomposition of the hydrogen peroxide and a considerable period of soaking of the lenses in the sterile water which remains of the solution after decomposition of the hydrogen peroxide.
While the apparatus employed in the above-referenced patent has met with commercial success, there is nonetheless room for further improvement. More particularly, one apparatus currently in use employs a plastic carrier member which is coated with a suitable platinum catalytic agent, and which is generally disposed in the bottom of a cylindrical container. The container is then filled with the hydrogen peroxide solution and the contact lenses, which are held in a further lens carrier/lens support case member, are then disposed within the container. Generally speaking, the lens support or lens carrier members are well-ventilated basket-like structures which are affixed to a cap member which in turn forms a cap or top closure for the solution-filled container. It is important, however, to provide some venting of the cap portion of the closure to control pressure buildup by permitting the escape of some of the free oxygen generated during the decomposition of the hydrogen peroxide solution.
While this system has proven highly successful in operation, there is, as mentioned above, room for improvement. For example, it is necessary for the user to periodically handle the "catalyst" which has the coating of catalyst material. That is, the catalyst material is consumed over a period of use, and therefore the catalyst member must be removed and replaced with a new catalyst from time to time. Handling by the consumer has a number of drawbacks. Some of the platinum coating of the carrier may rub off onto the fingers and cause undesirable staining of the skin and/or clothing of the user. Moreover, various proteins, salts, etc., from the skin might compromise the integrity and action of the catalyst. It appears that to some extent sulfur compounds and the proteins in the skin may combine with the platinum to form an inert compound. Moreover, with the catalyst member disposed in the bottom of the container, it is somewhat difficult to reach it manually without the use of some sort of tool, or the like.
There is also some concern that with the catalyst sitting in the bottom of the container between uses and after rinsing the container following a use, that some excess water may be trapped or entrained around the catalyst member which may give some potential for bacterial growth.